Fresh details from Tiahleigh Palmer police statement

DISTURBING new details from an unearthed police statement have revealed how 12-year-old Tiahleigh Palmer's body was stuffed in the boot of a car by her foster father.

Rick Thorburn, who was sentenced to life imprisonment on Friday for the sickening murder, was being watched by his wife Julene as he backed his blue Ford Falcon into a shed shortly after the killing in September 2015.

According to the statement to police in 2016, Julene couldn't see what her husband was doing in the shed for half an hour at around 8pm that night because her view was blocked by trees - but she knew her dead foster daughter was being loaded into the boot.

Details of the statement, obtained by ABC, also reveal how Rick ordered his teenage sons Joshua and Trent Thorburn to leave the house and go to places where they could be seen by other people as he worked to dispose the body.

"Don't ask any questions … try to be normal - the less you know, the better," Rick told the family the night he stuffed Tiahleigh's body in his car, according to Julene's statement.

Fishermen found Tiahleigh’s badly decomposed body floating in the Gold Coast’s Pimpama River

Rick Thorburn continued the cover-up on Facebook.

In January 2015, she was sent to live with the Thorburns at their sprawling modern home with a swimming pool. It was located on an isolated stretch of road at Chambers Flat, in a rural pocket of strawberry farms and horse paddocks at Logan, south of Brisbane.

A schoolmate, Mia Sky-Pfingst, described how Tia "made a world full with joy and happiness … we did everything together, like, get in trouble together, messed around a lot, played games".

But inside the four-bedroom brick house, Tiahleigh was to endure misery and sexual abuse.

Alarm bells were set off in her former carer, Ms Pemburton's mind when Tiahleigh occasionally played truant from school and told her she "hated" her new home, although the exact nature of her misery wasn't clear.

The Thorburns' younger son Trent, 18, described himself as a dancer, metal fabrication apprentice and classic car builder.

The blond selfie-obsessed Trent had started taking "advantage of (Tiahleigh) as her big brother".

At some point, he had become concerned he had impregnated Tiahleigh, who had also told a friend that Trent was having sex with her when Julene left the house.

About September 27, 2015, Trent confessed his wrongful relationship to a cousin, who then told Julene.

The 12-year-old schoolgirl's days were numbered; within 48 hours she would be dead.

Rick Thorburn would later tell police that he had dropped Tiahleigh off at school at 8.10am on Friday, October 30.

Trent Thorburn was charged with incest, pervert the course of justice and perjury. Picture: Instagram.

That morning, Joshua Thorburn was told not to go into his foster sister's room.

He walked past her door but did not look.

His father Rick had smothered Tiahleigh the night before to prevent any scandal about brother Trent's sexual relationship with a child.

Josh would later lie to police, telling them he'd spoken to Tiahleigh in the morning as she'd been getting ready for school, before she run away.

But it was his mother Julene who had orchestrated the cover-up, because she did not want to lose her "family and lifestyle".

Julene and Rick held a family meeting with Trent and Josh, telling the boys "it's all been taken care of".

That evening on Facebook, Rick Thorburn advanced the lie, posting messages about the girl's disappearance and garnering sympathy and help.

"If any of her friends are hiding her again, please do the right thing and let us know," he wrote at 11pm on the Friday. "She needs to come home where she belongs."

Six days later, three fishermen found Tiahleigh's badly decomposed body floating in the Gold Coast's Pimpama River, 30km south of where she was last seen.

Queensland detectives, who had suspected Rick Thorburn from the earliest days of their murder investigation, placed listening devices in the Chambers Flat house.

Tiahleigh Palmer didn’t have a chance once she went to live at the Thorburn’s house in idyllic countryside.

Julene Thorburn orchestrated the cover-up of husband Rick’s murder of Tiahleigh to keep her family together on the farm. Picture: Darren England

Rick Thorburn carries Tiahleigh’s white coffin nine days after murdering the 12-year-old and dumping her body.

In September 2016, police seized a car once owned by Rick Thorburn and took all four members of the family in for questioning.

Forensic officers began to dig up the backyard at Chambers Flat, searching for Tiahleigh's still missing school uniform and backpack.

Detectives charged Rick Thorburn with Tiahleigh's murder and with interfering with a corpse.

They charged Julene and Josh Thorburn with perjury and attempting to pervert the course of justice.

Trent Thorburn was charged with incest, attempting to pervert the course of justice and two counts of perjury.

Trent and Rick Thorburn were denied bail, and the father collapsed and was taken to hospital for a suspected heart attack.

Last year, Trent Thorburn began a maximum four-year, minimum five-month sentence for incest and his other charges.

Joshua Thorburn received a three month sentence, and Julene a maximum 18 months.

Rick Thorburn will spend the rest of his life in jail after pleading guilty to murdering the 12-year-old. He will need to serve 20 years in prison before being eligible for parole on September 12, 2036.